if by "the US" you mean "the federal government of the united states of america", than the words you are looking for are "constitutional republic". if by "the

if by "the US" you mean "the federal government of the united states of america", than the words you are looking for are "constitutional republic". if by "the US" you mean "the collection of various states that make up the members of the federal government of the united states of america", than there isn't one single concept that can be applied universally. different states have different types of governments - some are even commonwealths, not states!